Antibiotic CC-1065 is disclosed and claimed by its chemical and physical parameters in U.S. Pat. No. 4,169,888. Subsequently, the structure of antibiotic CC-1065 was elucidated as disclosed in "Structure Proof of Antibiotic CC-1065", D. G. Martin, C. G. Chidester, D. J. Duchamp, and S. A. Mizsak, J. Antibiot., 33 902 (1980). Antibiotic CC-1065 consists of a three-fragment system with the most labile portion of the molecule being the fragment named 1,2,8,8a-cyclopropa[c]benzo[1,2-b:4,3-b']dipyrrol-4(5H)-one. Attempts to obtain this fragment by degradation of antibiotic CC-1065 have not been published.
Wierenga U.S. Pat. No. 4,424,365 discloses and claims compounds of the formula ##STR4## wherein R.sub.2 and R.sub.3 are H, alkyl of from 1 to 5 carbon atoms, inclusive, and phenyl; R.sub.4 is selected from the group consisting of SO.sup.2 R.sub.2, SO.sub.2 CH.sub.2 --COphenyl, CO.sub.2 CH.sub.2 Z where Z is selected from the group consisting of CH.sub.2 I, CCl.sub.3, CH.sub.2 SO.sub.2 R.sub.2, phenyl, and fluorenylmethyl.
The Wierenga '365 patent also discloses in Chart 2 thereof a multi-step process for preparing 1,2,8,8a-cyclopropa[c]benzo[1,2-b:4,3-b']dipyrrol-4(5H)-one compounds, starting from 2-chloro-5-(oxy-ether)nitrobenzene. That process proceeds from the above-substituted nitrobenzene through the first step-aromatic nucleophilic substitution (replacing the 2-chloro group), followed by a reduction step (Step 2) to form the 2-[bis(hydroxymethyl)methyl]-5-(oxy-ether)-nitrobenzene (3). In Step 3 of Chart 2 of the Wierenga '365 patent, the hydroxy groups are replaced with functional groups (funtional group interchange), for example, with mesylate or tosylate groups using the corresponding sulfonyl chloride with or without the presence of pyridine, with or without the presence of an inert solvent such as methylene chloride, or other acid acceptors such as a trialkyl-amine. Thereafter, in Step 4 of that '365 patent, Chart 2 process the nitro group is reduced to the amino group (not shown in the '365 patent) with concomitant intra-molecular cyclization to give an N--H (unsubstituted) indoline which is further reacted in situ to give the indoline (dihydro-indole) compound of the formula ##STR5## as shown in U.S. Pat. No. 4,424,365 from which compound (5) the therein disclosed process proceeds through several more steps to the therein desired 1,2,8,8a-cyclopropa[c]benzo[1,2-b:4,3-b']dipyrrol-4(5H)-one.
However, in further study of this overall process we have found that the above sulfonylated aminobenzene/intermediate compounds are somewhat unstable and are not as easy to work with when larger scale operation of the overall process is contemplated.